Controlling reverse channel activity in a wireless communications system

ABSTRACT

A wireless communications system includes access networks and access terminals. Within each cell or cell sector, reverse links and forward links are defined between an access network and multiple access terminals in the cell or cell sector. Based on a reverse data rate threshold value calculated from noise measurements, the access network indicates to access terminals within its cell or cell sector whether activity on reverse links are to be increased or decreased.

TECHNICAL FIELD

[0001] This invention relates generally to controlling activity in areverse channel of a packet data wireless link.

BACKGROUND

[0002] Mobile communications systems are made up of a plurality ofcells. Each cell provides a radio communications center through which amobile station establishes a call or other communications session withanother mobile station or a terminal connected to either acircuit-switched network (e.g., public-switched telephone network orPSTN) or a packet-switched data network. Each cell includes a radio basestation, with each base station coupled to a switching center thatcontrols processing of calls or other communications sessions between oramong mobile stations or between mobile stations and terminals connectedto a circuit-switched or a packet-switched network.

[0003] Various wireless protocols exist for defining communications in awireless network. One type of protocol is based on the time-divisionmultiple access (TDMA) technology, such as the TIA/EIA-136 standardprovided by the Telecommunications Industry Association (TIA) or theGlobal System for Mobile (GSM) standard. Another type of protocol forwireless communications is based on the code-division multiple access(CDMA) technology. CDMA is a spread spectrum wireless communicationsprotocol in which transmission is based on the spread spectrummodulation technique to allow many users to have access to the same bandof carriers.

[0004] Traditionally, wireless networks have been designed for carryingcircuit-switched voice traffic. However, with the wide availability ofthe Internet and intranets, packet-switched communications (e.g., webbrowsing, electronic mail, instant messaging, electronic gaming, and soforth) have become common. As a result, third generation (3G) and beyondwireless technologies are being developed to provide higher bandwidthand more efficient packet-switched communications (of data as well asvoice and other forms of real-time data) over wireless networks.

[0005] In the CDMA context, a CDMA 2000 family of standards has beendeveloped that is capable of supporting both traditionalcircuit-switched traffic as well as packet-switched traffic. On the TDMAside, packet-switched wireless communications protocols have also beendeveloped.

[0006] The first phase of CDMA 2000 is referred to as 1×RTT (alsoreferred to as 3G1X or 1X), which is designed to increase voice capacityas well as to support data transmission speeds that are faster thantypically available. In addition, for even higher data rates, a HighRate Packet Data (HRPD) wireless technology has been developed. HRPD isdefined as TIA/EIA/IS-856, “CDMA 2000, High Rate Packet Data AirInterface Specification,” which is adopted by the TIA. The HRPDtechnology is also referred to as the 1×EV-DO or 1×EV technology.1×EV-DO provides relatively high data transfer rates over the airinterface between mobile stations and base stations.

[0007] In a 1×EV-DO network, the mobile station, rather than the basestation, controls the rate of data communicated in the reverse link(which is the link from the mobile station to the base station). Thus,multiple mobile stations in the wireless network can potentially setdifferent data rates over the reverse link. If the data rates in thereverse link are not controlled properly, the reverse link may either beunder-utilized (if the data rates are set to low) or excessiveinterference may result (if the data rates are set too high).

SUMMARY

[0008] In general, a mechanism is provided to efficiently control datarates in a reverse link of a packet data wireless link. For example, amethod of controlling data rates in a wireless communications systemincludes determining a condition of forward links between mobilestations and wireless access equipment, and computing a capacity ofreverse links between the mobile stations and the wireless accessequipment based on the condition of the forward links. The methodfurther includes indicating, based on the computed capacity, to at leastone of the mobile stations whether a data rate on the reverse linkbetween the at least one mobile station and the wireless accessequipment is to be increased or decreased.

[0009] Other or alternative features will become apparent from thefollowing description, from the drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a block diagram of an example arrangement of acommunications network that includes a packet data wireless network.

[0011]FIG. 2 shows the forward link and-reverse link physical channelstructures of the packet data wireless network of FIG. 1.

[0012]FIG. 3 is a flow diagram of a process of controlling data rates ofreverse links in the packet data wireless network of FIG. 1.

DETAILED DESCRIPTION

[0013] In the following description, numerous details are set forth toprovide an understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments may be possible.

[0014] Referring to FIG. 1, a wireless communications network 10 has acoverage area designated generally as 12. In one embodiment, thewireless communications network 10 includes components that operateaccording to the CDMA (code-division multiple access) 2000 protocol.CDMA 2000 is defined by the CDMA 2000 family of standards (collectivelyreferred to as the IS-2000 Standard, which is developed by the ThirdGeneration Partnership Project 2 (3GPP2)). In other embodiments, othertypes of wireless protocols, such as TDMA (time-division multipleaccess) protocols, can be used for communications in the wirelesscommunications network 10.

[0015] For circuit-switched communications, the wireless communicationsnetwork 10 includes a base station (BS) 14, which is an entity used forradio telecommunications with mobile stations (e.g., mobile station 16)within a cell or cell sector 18 covered by the base station 14. Forcommunicating circuit-switched voice traffic, the base station 14 iscoupled to a mobile switching center (MSC) 24, which is responsible forswitching mobile station-originated or mobile station-terminatedtraffic. Effectively, the MSC 24 is the interface for signaling and usertraffic between the wireless network 10 and other public-switchednetworks (such as a public-switched telephone network (PSTN) 26 or otherMSCs). The PSTN 26 is connected to landline terminals, such as telephone28.

[0016] In addition to circuit-switched services, the base station 14 canalso support packet data communications, in which packet data iscommunicated between a mobile station and another endpoint, which can bea terminal coupled to a data network 34 or another mobile station thatis capable of communicating packet data. Examples of the data network 34include private networks (such as local area networks or wide areanetworks) and public networks (such as the Internet). In one example,the base station 14 is part of a 1×RTT system, which supports packetdata services through the use of a packet control function (PCF) module32 and a packet data serving node (PDSN) 30. The base station 14 and PCFmodule 32 are optional components that may be omitted in someembodiments.

[0017] Packet data services involve packet-switched communications. Insome embodiments, packet-switched communications are defined by theInternet Protocol (IP). In packet-switched communications, packets orother units of data carry payload (including user data) as well asrouting information (in the form of addresses) used for routing thepackets or data units over one or more paths of the network to adestination endpoint. One version of IP, referred to as IPv4, isdescribed in Request for Comments (RFC) 791, entitled “InternetProtocol,” dated September 1981; and another version of IP, referred toas IPv6, is described in RFC 2460, entitled “Internet Protocol, Version6 (IPv6) Specification,” dated December 1998.

[0018] In addition to, or in place of, units that are part of a 1×RTTsystem, the wireless communications network 10 also includes a 1×EV-DOor 1×EV system that supports packet data services. One version 1×EV-DOis defined in the TIA/EIA/IS-856 standard, entitled “CDMA 2000 High RatePacket Data Air Interface Specification.” The 1×EV-DO (or HRPD) wirelesscommunications system includes an access network (AN) 40, which includesnetwork equipment (such as a base station and other controllers) thatprovides data connectivity between a packet-switched data network (suchas the data network 34) and a mobile station 43 (also referred to as an“access terminal” ). The access network 40 provides coverage in a cellor cell sector 41. More generally, reference is made to a “cellsegment,” which refers to either a cell or cell sector. Also, “mobilestation” generally refers to either a mobile station or an accessnetwork. Although one implementation is described in the context a1×EV-DO system, other types of wireless systems can be used in otherimplementations.

[0019] Other embodiments of the invention can be applied to otherpacket-based wireless protocols, such as the 1×EV-DV protocol (anotherCDMA2000-based protocol that integrates both voice and data), UMTS(Universal Mobile Telecommunication System) protocol (based on thewideband CDMA protocol), and MCDV (multi-carrier data-voice) protocol(from Nortel Networks).

[0020] The access network 40 is coupled to the PDSN 30 to enablepacket-switched communications with the packet-switched data network 34.A packet control function (PCF) module 46 is connected between theaccess network 40 and the PDSN 30. During a communications session,packet data is routed between the access terminal 43 and anotherendpoint through the access network 40, PCF module 46, and PDSN 30.

[0021] As further shown in FIG. 1, the wireless link between the accessterminal 43 and the access network 40 includes a forward link 50 (fromthe access network to the access terminal) and a reverse link 52 (fromthe access terminal to the access network). Generally, the forward link50 refers to a wireless link to communicate data and signaling from amobile station to wireless access equipment in a cell or cell sector,and the reverse link 52 refers to a wireless link to communicate dataand signaling from the wireless access equipment to the mobile station.“Wireless access equipment” refers to any one of an “access network,”“base station,” or other network equipment capable of wirelesslycommunicating with mobile stations.

[0022] In a 1×EV-DO system, the access network 40 does not directlycontrol data rates in the reverse link. Instead, each access terminalselects its data rate in the reverse link. “Data rate” in a wirelesslink refers to the rate of transfer, usually expressed inbits-per-second, of data (such as user traffic) over the link. The datarate determined by the access terminal is based on several factors,including a reverse activity bit (RAB) and other factors, as defined bythe 1×EV-DO standard.

[0023] As shown in FIG. 2, RAB is communicated by the access network toeach access terminal within the corresponding cell or cell sector in aforward channel 106 of the forward link. Generally, the RAB is anindicator communicated by wireless access equipment to a mobile stationto indicate whether activity in the reverse link should be increased ordecreased. The RAB is carried in a reverse activity channel 100, whichis part of medium access control (MAC) channel 110 of the forwardchannel 106. The forward MAC channel 110 also carries a DRCLock bit 102and a reverse power control channel 104 (for controlling the power ofthe reverse channel for a given access terminal).

[0024] The forward channel 106 also includes a forward pilot channel 108(which carries the pilot), a forward control channel 112 (which carriescontrol signaling and other data to be received by all access terminalsmonitoring the forward channel 106), and a forward traffic channel 114(which carries information to a specific access terminal).

[0025] In the reverse link, a reverse channel 116 includes a reverseaccess channel 118 (which is used by access terminals to communicatewith the access network when the access terminals do not have a trafficchannel assigned) and a reverse traffic channel 124 (which is theportion of the reverse channel 116 that carries information from aspecific access terminal to the access network).

[0026] The reverse access channel also 118 includes a reverse accesspilot channel 120 (which is the portion of the access channel 118 thatcarries a pilot) and a reverse access data channel 122 (which is theportion of the access channel 118 that carries data). The reversetraffic channel 124 includes a reverse traffic pilot channel 126 (whichcarries the pilot in the reverse traffic channel 124), a reverse MACchannel 128 (which is the portion of the reverse traffic channel 124dedicated to MAC activities), a reverse traffic Ack channel 130 (whichindicates the success or failure of forward traffic channel reception),and a reverse traffic data channel 132 (which is the portion of thereverse traffic channel 124 that carries user data).

[0027] The reverse traffic MAC channel 128 contains a reverse rateindicator (RRI) channel 134 and a data rate control (DRC) channel 136.The RRI channel 134 is set by an access terminal to indicate (to theaccess network) the data rate of the reverse traffic data channel 132.The DRC channel 136 is used by the access terminal to indicate to theaccess network the requested forward traffic channel data rate and theselected serving cell sector on the forward channel 106. As discussedbelow, the RRI information and DRC information are used by the accessnetwork 40 to control the data rate of the reverse link.

[0028] In accordance with some embodiments of the invention, the stateof RAB, which is communicated in the forward MAC reverse activitychannel 100, is set by the access network 40 based on an estimatedcapacity of the reverse link 52. The estimated capacity of the reverselink 52 is calculated from data rates of the forward traffic channels124, as indicated by the DRC channels 136, between access terminals inthe cell sector and the access network.

[0029] The state of RAB controls whether data rate of the reverse linkis to be increased or decreased. If RAB is at a first state, then eachaccess terminal in the cell sector increases its data rate on thereverse link under certain conditions. On the other hand, if RAB is at asecond state, then each access terminal in the cell sector decreases itsdata rate on the reverse link under certain conditions.

[0030]FIG. 3 shows a flow for determining the state of RAB, according toone embodiment. The flow has two phases: an initialization (orcalibration) phase 200 and an operation phase 202. Generally, theinitialization phase 200 is computation intensive and requires someamount of time for the access network to perform. Therefore, theinitialization phase is not performed continuously, but rather, isperformed either periodically or in response to defined events. On theother hand, the operation phase 202 of the flow is performedsubstantially continuously to control the data rate of the reversetraffic data channel 132. In other words, the operation phase 202 isperformed more frequently than the initialization phase 200.

[0031] In the initialization phase 200, calibration of RRI values(representing data rates of the reverse link) and DRC values(representing data rates of the forward link) is performed (at 204) bythe access network 40. Each RRI value represents the data rate of thereverse link between a given access terminal and the access network 40.Each DRC value represents the data rate of the forward link of the givenaccess terminal and the access network 40.

[0032] In the calibration process (204), a noise threshold L_(t) is set(at 204A) to a predefined value that represents a level of acceptablenoise on the reverse link due to traffic activity. The predefined valueof the noise threshold L_(t) is set, based on empirical data, at a levelthat maximizes traffic while maintaining the noise level at anacceptable level.

[0033] Calibration is performed by setting (at 204B) RAB to the logical0 state so that traffic data rates in the reverse links (from the accessterminals in the cell sector to the access network) are increased (bythe access terminals). The access network 40 measures (at 204C) thenoise level of the reverse links until the threshold L_(t) is reached.Measuring the noise level is performed by measuring the total powerreceived by the transceiver in the access network 40. Accuratemeasurements usually require some amount of time (on the order ofminutes).

[0034] Once the L_(t) noise level is reached, the access network 40records the relationship between the forward link data rates (DRC) andreverse link data rates (RRI). In response to the noise threshold L_(t)being reached, the individual DRC_(i) values of the access terminalsMS_(i) in a cell sector are summed (at 206) to produce a parameterDRC_tot(t):${{{DRC\_ tot}(t)} = {\sum\limits_{i}{\log_{10}\left( {{DRC}_{i}(t)} \right)}}},$

[0035] where DRC_(i)(t) represents the DRC value of access terminalMS_(i) at time t, and DRC_tot(t) represent the summed value of thelogarithm of individual DRC₁(t) values. Each DRC_(i) value is a functionof the propagation loss of the wireless link between the access networkand the access terminal. The higher the propagation loss, the lower thedata rate has to be set. Thus, DRC_(i) represents a condition of theradio frequency (RF) link between the access network and the accessterminal. DRC_tot thus represents the cumulative condition of the RFlinks between the access terminals served by the access network in thecorresponding cell sector.

[0036] Next, the access network 40 computes (at 208) the reverse channelcapacity. The reverse channel capacity is defined as the cumulativeactivity level of the reverse links between access terminals in the cellsector and the access network once the noise threshold L_(t) has beenreached. The reverse channel capacity is represented by RRI_tot_(th),which is a threshold value to represent the sum of the logarithm of allRRI₁ values of access terminals served by the access network.RRI_tot_(th) is calculated based on the value of DRC_tot(t) at the timewhen the noise on all reverse links has reached the threshold noiselevel L_(t).

[0037] In one implementation, the relationship of DRC and RRI isexpressed as:${{\sum\limits_{i}{\log_{10}\left( {RRI}_{i} \right)}} = {{\sum\limits_{i}{\log_{10}\left( {DRC}_{i} \right)}} + {{constant}\quad {value}}}},$

[0038] where RRI₁ represents the RRI value for the reverse link betweenaccess terminal MS_(i) and the access network 40, and DRC₁ representsthe DRC value for the forward link between the access network 40 and theaccess terminal MS₁.

[0039] Several measurements are taken at different times during theinitialization phase 200. Because of movement in the cell sector andpossibly different numbers of active mobile stations, the DRC_tot(t)values measured at different times will be different, which means thatthe corresponding RRI_tot_(th) value will be different. The relationshipbetween the DRC_tot(t) values and corresponding RRI_tot_(th) values arerecorded (at 209). In one example, this relationship can be in the formof a lookup table.

[0040] The relationship between DRC_tot(t) and RRI_tot_(th) values isused during the operation phase to set the state of RAB in the forwardMAC reverse activity channel 100 to control whether activity in thereverse traffic data channel 132 is to be increased or decreased.

[0041] Acts 204, 206, 208, and 209 are performed in the initializationor calibration phase 200. As noted above, the calibration phase isperformed periodically or in response to defined events. On the otherhand, the operation phase 202 is performed more frequently. In theoperation phase, the access network 40 calculates the DRC_tot(t) value:${{DRC\_ tot}(t)} = {\sum\limits_{i}{{\log_{10}\left( {{DRC}_{i}(t)} \right)}.}}$

[0042] From the calculated DRC_tot(t) value, the access network 40accesses (at 211) the relationship (e.g., lookup table) to determine thecorresponding RRI_(—tot) _(th) value. Next, the access network 40calculates (at 212) RRI_tot(t):${{{RRI\_ tot}(t)} = {\sum\limits_{i}{\log_{10}\left( {{RRI}_{i}(t)} \right)}}},$

[0043] where RRI_(i) (t) represents the RRI value for access terminalMS_(i) at time t (in other words, the data rate of the reverse link foraccess terminal MS_(i) at a given time). RRI_tot(t) represents the sumof all RRI₁ values at time t. The calculated RR_tot(t) value is compared(at 214) against the threshold value RRI_tot_(th), (identified at 211).If RRI_tot(t) is greater than or equal to the threshold valueRRI_tot_(th), then the RAB value is set (at 216) to logical 1. Thisindicates that there is too much activity in the reverse links and theaccess terminals are instructed to reduce their data rates.

[0044] On the other hand, if RRI_tot(t) is less than the threshold valueRRI_tot_(th), the availability of physical resources at the accessnetwork 40 is checked (at 218). Physical resources refer to the hardwareelements available in the access network 40. Availability of suchhardware elements determine whether increased data activity can besupported. The state of a logical variable R is set (at 218) accordingto whether physical resources are available or not. If physicalresources are available, then R is set to logical true; otherwise, R isset to logical false. Next, the access network determines (at 220) if Rhas the logical true or false state. If R has the logical true state,then that indicates that there are not enough physical resources and thestate of RAB is set (at 216) to logical 1. On other hand, if R has thelogical false, then the access network sets (at 222) the state of RAB tological 0.

[0045] An access terminal performs rate control using the received stateof RAB. The state of RAB affects a variable MaxRate in each accessterminal, with MaxRate specifying a maximum data rate in the reversetraffic data channel 132 from the access terminal to the access network.MaxRate is based on the current transmission rate of the accessterminal, the state of RAB, and a random number. Generally, if theaccess terminal receives RAB set to logical 0, then the value of MaxRateis increased or set at the same value based on the value of thegenerated random number. However, if the received RAB value has thelogical state 1, then the value of MaxRate is either maintained at thesame value or decreased based on the generated random number. Thus,effectively, RAB set to the logical value 0 allows an access terminal toincrease its data rate on the reverse traffic channel if certainconditions are satisfied.

[0046] Effectively, in the procedure outlined in FIG. 3, a thresholdreverse data rate (representing the cumulative reverse data rates of allaccess terminals in a cell sector) is set during the initializationphase 200. The threshold reverse data rate is computed from forward datarate values once activity in the reverse link has been measured to havereached a threshold level. The threshold reverse data rate represents anestimated capacity of the reverse link. This threshold reverse data rateis used to determine whether RRI₁ values (during operation of the accessnetwork 40) are too high or too low. Based on this determination, anindicator (RAB) is set by the access network 40 and communicated to allmobile stations in the cell sector to indicate whether activity (datarate) on the reverse links is to be increased or decreased.

[0047] The tasks performed by the access networks and access terminalsare provided by software routines or modules in the access networks oraccess terminals. Instructions of such software routines or modules arestored on one or more storage devices in the corresponding systems andloaded for execution on corresponding control units or processors. Thecontrol units or processors include microprocessors, microcontrollers,processor modules or subsystems (including one or more microprocessorsor microcontrollers), or other control or computing devices. As usedhere, a “controller” refers to hardware, software, or a combinationthereof. A “controller” can refer to a single component or to pluralcomponents (whether software or hardware).

[0048] Data and instructions (of the software) are stored in respectivestorage devices, which are implemented as one or more machine-readablestorage media. The storage media include different forms of memoryincluding semiconductor memory devices such as dynamic or static randomaccess memories (DRAMs or SRAMs), erasable and programmable read-onlymemories (EPROMs), electrically erasable and programmable read-onlymemories (EEPROMs) and flash memories; magnetic disks such as fixed,floppy and removable disks; other magnetic media including tape; andoptical media such as compact disks (CDs) or digital video disks (DVDs).

[0049] The instructions of the software are loaded or transported toeach entity in one of many different ways. For example, code segmentsincluding instructions stored on floppy disks, CD or DVD media, a harddisk, or transported through a network interface card, modem, or otherinterface device are loaded into the entity and executed ascorresponding software routines or modules. In the loading or transportprocess, data signals that are embodied in carrier waves (transmittedover telephone lines, network lines, wireless links, cables, and thelike) communicate the code segments, including instructions, to theentity. Such carrier waves are in the form of electrical, optical,acoustical, electromagnetic, or other types of signals.

[0050] While the invention has been disclosed with respect to a limitednumber of embodiments, those skilled in the art will appreciate numerousmodifications and variations there from. It is intended that theappended claims cover such modifications and variations as fall withinthe true spirit and scope of the invention.

What is claimed is:
 1. An article comprising at least one storage mediumcontaining instructions that when executed cause wireless accessequipment in a cell segment to: measure activity on reverse linksbetween mobile stations in the cell segment and the wireless accessequipment; determine a threshold capacity of the reverse links inresponse to detecting the activity reaching a predefined thresholdlevel; and subsequently, during operation of the wireless accessequipment, using the threshold capacity to set one or more indicationsof whether to increase or decrease activity on the reverse links.
 2. Thearticle of claim 1, wherein the instructions when executed cause thewireless access equipment to communicate the one or more indications tothe mobile stations.
 3. The article of claim 2, wherein the instructionswhen executed cause the wireless access equipment to communicate the oneor more indications by communicating a reverse activity bit to themobile stations, the reverse activity bit defined by a code-divisionmultiple access (CDMA) high rate packet data (HRPD) protocol.
 4. Thearticle of claim 3, wherein the instructions when executed cause thewireless access equipment to set the reverse activity bit to a firststate to indicate that activity on the reverse links is to be increased,and to set the reverse activity bit to a second state to indicate thatactivity on the reverse links is to be decreased.
 5. The article ofclaim 1, wherein the instructions when executed cause the wirelessaccess equipment to communicate the one or more indications to themobile stations, the one or more indications defined by one of a 1×EV-DOprotocol, 1×EV-DV protocol, UMTS protocol, and multi-carrier data-voiceprotocol.
 6. The article of claim 1, wherein the instructions whenexecuted cause the wireless access equipment to perform the measuringand determining during a calibration phase.
 7. The article of claim 6,wherein the instructions when executed cause the wireless accessequipment to perform the operation substantially continuously butperform the calibration phase less frequently.
 8. The article of claim1, wherein the instructions when executed cause the wireless accessequipment to use the threshold capacity to set the one or moreindications by: calculating a sum of data rates of the reverse link;comparing the sum to the threshold capacity; setting the one or moreindications to increase activity in response to the sum being less thanthe threshold capacity; and setting the one or more indications todecrease activity in response to the sum being greater than thethreshold capacity.
 9. The article of claim 1, wherein the instructionswhen executed cause the wireless access equipment to measure activity bymeasuring an amount of noise received by the wireless access equipment.10. The article of claim 9, wherein the instructions when executed causethe wireless access equipment to determine the threshold capacity bydetermining a sum of the data rates on the reverse links at the timethat the noise has reached the predefined threshold level.
 11. Thearticle of claim 10, wherein the instructions when executed cause thewireless access equipment to receive an indicator of data rate of eachreverse link from a corresponding wireless access equipment.
 12. Thearticle of claim 10, wherein the instructions when executed cause thewireless access equipment to compute a sum of data rates of forwardlinks between the mobile stations and the wireless access equipment,wherein determining the sum of the data rates on the reverse links isbased on the computed sum of data rates of the forward links.
 13. Amethod of controlling data rates in a wireless communications system,comprising: determining a condition of forward links between mobilestations and wireless access equipment; computing a capacity of reverselinks between the mobile stations and the wireless access equipmentbased on the condition of the forward links; and indicating to at leastone of the mobile stations whether a data rate on the reverse linkbetween the at least one mobile station and the wireless accessequipment is to be increased or decreased, wherein the indicating isbased on the computed capacity of the reverse links.
 14. The method ofclaim 13, wherein determining the condition of forward links comprisesdetermining based on data rates of the corresponding forward links. 15.The method of claim 14, further comprising correlating the data rates ofthe forward links to data rates of the reverse links, wherein computingthe capacity of the reverse links is based on the correlation of thedata rates of the forward links and data rates of the reverse links. 16.The method of claim 15, wherein correlating the data rates comprises:measuring noise of the reverse links while traffic on the reverse linksis increased until a threshold noise level is reached; and computing thecapacity of the reverse links based on a sum of data rates on theforward links at a time when the noise on the reverse links has reachedthe threshold noise level.
 17. The method of claim 16, wherein thewireless communications system includes a code-division multiple access(CDMA) high rate packet data (HRPD) wireless system, the method furthercomprising: and calculating a sum of data rate control (DRC) values, theDRC values representing the data rates on the forward links.
 18. Themethod of claim 17, wherein calculating the sum of DRC values comprisescalculating the sum of a log of each DRC value.
 19. The method of claim13, wherein determining the condition of the forward links comprisesdetermining the condition of CDMA HRPD forward links, and whereincomputing the capacity of reverse links comprises computing the capacityof CDMA HRPD reverse links.
 20. The method of claim 13, furthercomprising performing the determining and computing during a calibrationphase and the indicating during an operation phase.
 21. The method ofclaim 20, wherein the calibration phase is performed less frequentlythan the operation phase.
 22. The method of claim 20, furthercomprising, during the operation phase: calculating a sum of data ratesof the reverse links indicated by mobile stations; and comparing thecalculated sum to the computed capacity of reverse links.
 23. The methodof claim 22, wherein indicating whether the data rate on the reverselink is to be increased or decreased comprises communicating anindicator to the at least one mobile station, the indicator having oneof two states.
 24. The method of claim 22, wherein the wirelesscommunications system includes a CDMA HRPD wireless system, whereincalculating the sum of data rates of the reverse links comprisescalculating the sum of reverse rate indicator (RRI) values.
 25. Themethod of claim 13, wherein determining the condition of forward linksbetween mobile stations and wireless access equipment comprisesdetermining the condition of forward links defined by one of a 1×EV-DOprotocol, 1×EV-DV protocol, UMTS protocol, and multi-carrier data-voiceprotocol.
 26. A system comprising: an interface adapted to communicateover wireless forward links and wireless reverse links with mobilestations; and a controller adapted to compute a capacity of the reverselinks, to monitor a level of usage of the reverse links, and tocommunicate one or more indicators to the mobile stations to indicatewhether data rates on the reverse links are to be increased or decreasedbased on a comparison of the usage of the reverse links and the computedcapacity.
 27. The system of claim 26, wherein the controller is adaptedto communicate the one or more indicators by communicating a reverseactivity bit to the mobile stations, the reverse activity bit defined bya code-division multiple access (CDMA) high rate packet data (HRPD)protocol, the reverse activity bit set to a first state to indicate thatactivity on the reverse links is to be increased, and set to a secondstate to indicate that activity on the reverse links is to be decreased.28. The system of claim 26, wherein the controller is adapted to computethe capacity of the reverse links by computing a sum of data rates offorward links between the mobile stations and the system.